OFFSHORE STRUCTURES REPORT Potential of concrete structures in WA for offshore, marine and resource infrastructure by Krish Thiagarajan For the Concrete Offshore Structures Industry (COSI)* Committee, Western Australia The future demand for concrete in offshore oil and gas, mining and maritime industries will be very strong. Marine concrete is a reliable and time-tested material for oil and gas production platforms (broadly known as Concrete Gravity Structures (CGS)) and support structures such as foundations piles, storage tanks and vessels. This report, prepared on behalf of the Concrete Offshore Structures Industry (COSI) Committee, presents to industry the current state-of-the- art for concrete utilisation in various marine and offshore applications. Apart from these key oil and gas items, coastal structures such as breakwaters and wharves as well as pump stations, bridges and subsurface tunnels are made from concrete. The potential for construction and fabrication of concrete structures in Western Australia has been clearly demonstrated in the past. Perhaps the biggest success story in this context is the Wandoo B oil production and storage platform. This 81,000t CGS, built in the Bunbury casting basin in 1995-96, was constructed with a rectangular base and four columns. Construction was in stages using a slip-forming process. On completion the CGS was fl oated out of the casting basin and towed to its location on the North West Shelf, where it was ballasted and anchored on the seabed. The Australian Marine Complex (AMC) Common User Facility located in Western Australia, at Henderson 35km south of Perth, is a potential location for undertaking major concrete construction and casting. Excellent support infrastructure and services are available at the AMC for fully developing a local concrete construction industry. When construction is completed, the concrete structures could be loaded out at the AMC wharf facilities and then towed to site on the North West Shelf or to other Asia-Pacific locations. Good proximity and access to the region’s major oil and gas industry companies is an added advantage of the existing and potential concrete construction facilities in Western Australia. Very signifi cant economic benefi ts accrue from concrete construction projects, with increased employment opportunities resulting. The construction methods used on the Wandoo CGS project can be applied to various remote area developments. Similar construction processes could be particularly benefi cial to the billions of dollars of proposed marine, mining and oil and gas projects in northern or remote WA. Designers and contractors may need to consider applying the Wandoo CGS principles, possibly in smaller modular form, to realise the benefits of precasting concrete structures locally in Perth, and then Tow-out of the Wandoo CGS platform from Bunbury, WA. PHOTO: WANDOO ALLIANCE Concrete in Australia Vol 34 No 3 37